1. Field of the Invention
The present invention relates to a mobile information apparatus capable of operating in a plurality of operation modes.
2. Description of the Related Art
In recent years, a variety of mobile information apparatuses have been widely used. Examples of such mobile information apparatuses include handheld computers, electronic dictionaries, and head-mounted displays. In particular, cell phones are an example of the mobile information apparatuses which many people carry around with them for a long time.
Cell phones are provided in various forms. For example, a widely known cell phone has a first body of equipment and a second body of equipment connected to the first body of equipment with a hinge in a flip-open and flip-close manner. A cell phone having such a structure is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 8-298538.
Some models of such cell phones have not only a telephone function but also a function for transmitting and receiving a variety of information via the Internet and a function for capturing still and moving images with a built-in camera and externally transmitting the images. In recent years, cell phones have become much more multifunctional.
On the other hand, display apparatuses which are mounted on the human head to view an image have been known. Examples of the display apparatuses include a head-mounted display (HMD) and a head-up display (HUD).
Such a display apparatus is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2003-248194. In a video display apparatus disclosed in this publication, a light-emitting diode and a liquid crystal display element are arranged at positions corresponding to the frames of glasses in order to produce an image. The produced image is projected onto holographic optical elements arranged at positions corresponding to lenses of the glasses as a combiner. An image reflected by the holographic optical elements is led to observer's eyes. Thus, the image (i.e., a virtual image) is superimposed over an external world image and can be viewed by the observer.
However, since a cell phone is designed to be small and lightweight, the number of buttons operably arranged on a surface of the cell phone is limited. Accordingly, many functions are assigned to one button. If cell phones become more multifunctional, the operation of cell phones will become more complicated, and therefore, the operability of cell phones will significantly decrease.